The present invention relates to devices and methods for applying threads to supports, in particular supports of plastic or rubber, these devices and methods making it possible, for example, to produce reinforcement plies, in particular reinforcement plies for tires. The invention relates, in particular, to methods and devices which make it possible to apply threads to a support while imparting a nonrectilinear shape to them, for instance a sinuous shape.
Devices which make it possible to apply threads to a support while imparting a sinuous shape to them are described, for instance, in the following patents or patent applications: FR 2 042 859, FR 2 325 497, FR 2 501 126, SU 704, 816, WO 81/1151.
These devices have at least one of the following drawbacks:
complex character of the devices, giving rise to frequent breakdowns or making costly and frequent maintenance necessary; PA1 a lack of precision in the laying of the threads, so that the plies obtained have a heterogeneous geometry and therefore present physical properties which vary in accordance with their length. PA1 (a) each of the threads is fed with a controlled speed onto a cylindrical drum rotating around an axis; PA1 (b) the threads are imparted the nonrectilinear shape by means of teeth which are displaced with respect to each other parallel to the axis of rotation; PA1 (c) at least some of these teeth are flexible between a free end, in contact with a thread, and an anchoring zone; PA1 (d) due to the flexibility of the flexible teeth, the amplitude of displacement of each thread, measured parallel to the axis of rotation, is determined by the ratio between the speed of arrival of this thread and the peripheral speed of the drum; PA1 (e) the support or supports are caused to arrive in contact with the drum and the threads are applied to the support or supports after the threads have been displaced on the drum; PA1 (f) the ply or plies formed by the support or supports and by the threads in contact with said support, are removed from the drum. PA1 (a) it comprises a drum having means making it possible to drive the drum in rotation around an axis; PA1 (b) it comprises means making it possible to have the threads arrive, each with a controlled speed, onto the drum; PA1 (c) it comprises teeth and means making it possible to displace these teeth with respect to each other parallel to the axis of rotation, so as to impart the nonrectilinear shape to the threads; PA1 (d) at least some of these teeth are flexible between a free end in contact with a thread and an anchoring zone; PA1 (e) it comprises means making it possible to have the support or supports arrive in contact with the drum and of applying the threads on the support or supports after these threads have been displaced; PA1 (f) it comprises means making it possible to remove from the drum the ply or plies each formed by the support or supports and by the threads in contact with said support.
Application EP-A 318 791 describes a device for applying threads to a support using two clamps, a front clamp and a rear clamp as seen in the direction of advance of the support and of the threads, the device comprising means making it possible to open and close the clamps and means for displacing the rear clamp along the direction of advance or along a direction opposite to the direction of advance, as well as means for displacing the threads in transverse directions. The device described in said application EP-A-318 791 makes it possible to lay the threads with great precision, but the speed of laying is relatively slow due to the complex succession of movements of the clamps, which require stops of the support upon transverse movements of the threads before they are applied to the support and upon the application of the threads to the support.